1. Field of Use
The present invention relates to monitoring the operation of computer systems and, more particularly, to apparatus and methods for selecting and storing trigger patterns for detecting selected events in the operation of a computer system.
2. Prior Art
A recurring problem in monitoring the performance and operation of computer systems, for example, on a computer system bus during operation, is that of the ability of the user of a monitoring apparatus to select the conditions to be monitored and detected. The majority of system bus monitors of the prior art have detected events occurring in a system by means of combinatorial logic connected from either the points to be monitored, for example, the signal lines of a bus, or from the outputs of system circuits already present for detecting errors in the operation of the system, for example, parity checking circuits for detecting errors in the data communicated over a bus and timing circuits for detecting when a bus operation has failed to complete. The problem with such devices of the prior art is that the user of the apparatus has relatively little ability to select different, specific conditions to be detected. In addition, the selection process is usually quite cumbersome. For example, a system bus in a major system may contain eighty signal lines; there may therefore be up to 2.sup.80 different possible conditions of the bus to be monitored and the selection of conditions is often done by laboriously connecting input lines from the lines of the bus to the inputs of the combinatorial logic. In addition, and due to the complexity of the combinatorial logic necessary to identify and detect one or more single conditions of a large number of possible conditions, the user is often provided with logic circuits sufficient only to monitor for one or two conditions at a time.